Method of applying cationic coating to stud bolt

Abstract

To restrain a coating from being peeled from a stud bolt when a nut is being removed.SOLUTION: A method of applying cationic coating to a stud bolt includes the steps of: arranging a masking member on a plate surface; attaching a split nut to the stud bolt so as to engage with a screw groove of the stud bolt; attaching an outside member having a central hole to the split nut so that the inner peripheral surface of the central hole of the outside member contacts the outer peripheral surface of the cylindrical part of the split nut; pressurizing the masking member with the split nut by rotating the split nut around the stud bolt in the coupling direction; and performing a cationic coating to the stud bolt in the state of pressurizing the masking member by the split nut.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a method for cathodic coating a stud bolt.

[0002] Patent Document 1 discloses a technique for painting a stud bolt in a state where part of the outer peripheral surface of the stud bolt is masked with a masking member made of an elastic material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-021218 Summary of the Invention [Problem to be solved by the invention]

[0004] For electrical connection (e.g., earthing), cathodic paint coating may be applied to a stud bolt with its bearing surface masked. A masking method using a nut may be used to mask the bearing surface of a stud bolt. In this masking method, a masking member is placed on the bearing surface, and then a nut is fastened to the stud bolt, pressuring the masking member toward the bearing surface. Because the masking member adheres closely to the bearing surface, it is possible to effectively prevent paint from adhering to the bearing surface. Furthermore, when this masking method is used, the portion of the stud bolt that is closer to the tip than the nut is painted.

[0005] When using the above masking method (i.e., a masking method using a nut), it is necessary to remove the nut from the stud bolt after performing cationic coating. When removing the nut from the stud bolt, the nut passes over the tip portion of the stud bolt. At this time, the nut slides against the stud bolt, which may cause the paint to peel off from the tip portion of the stud bolt. This specification proposes a technology to prevent the paint from peeling off from the stud bolt when the nut is removed. [Means for solving the problem]

[0006] This specification proposes a method for cathodic coating of a stud bolt, which includes the steps of: placing a masking member on the bearing surface of the stud bolt; attaching a split nut, which has a cylindrical portion with a thread groove formed on the inner circumferential surface of a central hole and which can be circumferentially divided into multiple portions, to the stud bolt so that the thread groove of the central hole engages with the thread groove of the stud bolt and the split nut contacts the masking member; attaching an outer member having a central hole to the split nut so that the inner circumferential surface of the central hole of the outer member contacts the outer circumferential surface of the cylindrical portion; rotating the split nut in the fastening direction relative to the stud bolt to apply pressure to the masking member with the split nut; and performing cathodic coating on the stud bolt while the masking member is being applied pressure by the split nut.

[0007] In this method, the split nut is composed of multiple parts that can be separated in the circumferential direction. After the split nut is attached to the stud bolt, an outer member is attached to the outer peripheral surface of the split nut, thereby constraining the multiple parts of the split nut. Therefore, the split nut can be rotated in the fastening direction relative to the stud bolt, and pressure can be applied to the masking member. This prevents paint from adhering to the seating surface of the stud bolt during cathodic coating. When the outer member is removed from the split nut after cathodic coating, the split nut can be separated into multiple parts and removed from the stud bolt. Because the split nut can be removed from the stud bolt without passing through the tip portion of the stud bolt (i.e., the painted portion), peeling of the paint from the stud bolt can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. [Figure 2] An explanatory diagram of the painting process. [Figure 3] FIG. 2 is a perspective view of a modified example corresponding to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] FIG. 1 shows components used when cathodic coating a part 10 to be coated. Note that the dot-hatched surfaces in FIG. 1 represent surfaces on which thread grooves are provided. The part 10 to be coated has a metal plate 12 and a stud bolt 14 erected on the surface of the metal plate 12. The stud bolt 14 is welded to the metal plate 12. A thread groove is provided on the outer circumferential surface of the stud bolt 14. The surface of the metal plate 12 around the stud bolt 14 forms a bearing surface 16 for a nut fastened to the stud bolt 14. When coating the part 10 to be coated, masking is performed using a masking seal 20, a masking member 30, a split nut 40, and an outer nut 50.

[0010] The masking seal 20 is a ring-shaped seal. The stud bolt 14 can be inserted into the central hole of the masking seal 20. The masking seal 20 is attached to the seat surface 16.

[0011] The masking member 30 is a ring-shaped member. For example, the masking member 30 is made of an elastic member such as resin. The stud bolt 14 can be inserted through the central hole of the masking member 30. The masking member 30 is placed on top of the masking seal 20.

[0012] The split nut 40 has a cylindrical portion 40a and a flange portion 40b extending radially outward from the cylindrical portion 40a. The flange portion 40b is provided at the lower end of the cylindrical portion 40a. A thread groove is provided on the inner circumferential surface of the center hole of the cylindrical portion 40a. The center hole of the cylindrical portion 40a screws onto the stud bolt 14. A thread groove is provided on the outer circumferential surface of the cylindrical portion 40a. The split nut 40 is placed on top of the masking member 30.

[0013] The split nut 40 is circumferentially separable into two members 42, 44. That is, each of the members 42, 44 has an arc-shaped portion of the cylindrical portion 40a. In this embodiment, the split nut 40 is separable along a dividing plane along the radial direction. Note that in other embodiments, the split nut 40 may be separable into three or more members.

[0014] A thread groove is provided on the inner peripheral surface of the center hole of the outer nut 50. The outer nut 50 is screwed onto the outer peripheral surface of the cylindrical portion 40a of the split nut 40.

[0015] 2 shows the process of cathodic coating of the part 10 to be coated. First, as shown in FIG. 2(a), a masking sticker 20 is attached to the seating surface 16. Next, a masking member 30 is placed on the masking sticker 20.

[0016] 2(b), the split nut 40 is placed on the masking member 30 by combining the members 42 and 44 on the masking member 30. Here, the members 42 and 44 are combined on the masking member 30 so that the thread groove on the inner peripheral surface of the split nut 40 engages with the thread groove of the stud bolt 14. Also, here, the lower surface of the flange portion 40b of the split nut 40 is brought into contact with the upper surface of the masking member 30.

[0017] Next, as shown in FIG. 2(c), the outer nut 50 is threaded onto the cylindrical portion 40a so that the thread grooves of the outer nut 50 engage with the thread grooves on the outer peripheral surface of the cylindrical portion 40a. Because the upper end of the cylindrical portion 40a is tapered, when the cylindrical portion 40a is inserted into the central bore of the outer nut 50, the members 42 and 44 are pulled toward each other. This makes it easy to thread the outer nut 50 onto the cylindrical portion 40a. When the outer nut 50 is attached to the cylindrical portion 40a, the members 42 and 44 of the split nut 40 are constrained to each other. When the outer nut 50 is rotated in the fastening direction from the state shown in FIG. 2(c), the outer nut 50 comes into contact with the flange portion 40b as shown in FIG. 2(d). Here, the outer nut 50 is further rotated in the fastening direction from the state shown in FIG. 2(d). The outer nut 50 and the split nut 40 then rotate together in the fastening direction relative to the stud bolt 14. As a result, the split nut 40 is displaced toward the seating surface 16, and the masking member 30 and the masking seal 20 are pressed toward the seating surface 16. As a result, the masking seal 20 comes into close contact with the seating surface 16.

[0018] Next, as shown in Figure 2(e), the part 10 to be painted is subjected to cathodic painting. The surfaces of the stud bolt 14 and metal plate 12 are not painted in the areas covered by the masking seal 20, masking member 30, and split nut 40. In particular, because the masking seal 20 is pressed toward the bearing surface 16, it is possible to effectively prevent paint from adhering to the bearing surface 16. Therefore, a paint film 60 is formed on the tip portion 14a of the stud bolt 14 and on the area of ​​the upper surface of the metal plate 12 other than the bearing surface 16.

[0019] Next, as shown in FIG. 2(f), the outer nut 50 is removed from the split nut 40. Because a wide gap exists between the outer nut 50 and the stud bolt 14, interference between the outer nut 50 and the tip portion 14a of the stud bolt 14 is prevented when the outer nut 50 is removed. When the outer nut 50 is removed, the components 42, 44 of the split nut 40 are released from their restraint. Next, as shown in FIG. 2(f), the components 42, 44 are separated, thereby removing the split nut 40 from the stud bolt 14. When the split nut 40 is removed from the stud bolt 14 in this way, the split nut 40 does not come into contact with the tip portion 14a of the stud bolt 14, preventing the paint film 60 on the tip portion 14a from peeling off.

[0020] Next, as shown in FIG. 2(g), the masking member 30 and masking seal 20 are removed from the part 10 to be painted. This exposes the bearing surface 16 in an unpainted state. In this way, according to the method of the embodiment, cationic coating can be performed on the part 10 to be painted while preventing paint from adhering to the bearing surface 16. When a part is attached to the stud bolt 14 after painting, the part and bearing surface 16 come into contact with each other, thereby electrically connecting them. Furthermore, except for the area around the base of the stud bolt 14, cationic coating improves the appearance and provides rust prevention.

[0021] In the above embodiment, the masking member 30 is configured as a separate member from the split nut 40. However, the masking member 30 may be integrated with the split nut 40. In this case, a configuration can be adopted in which a part of the masking member 30 is fixed to the lower part of member 42 of the split nut 40, and the other part of the masking member 30 is fixed to the lower part of member 44.

[0022] In the above embodiment, the outer nut 50 is threaded into the thread groove on the outer peripheral surface of the split nut 40, thereby constraining the members 42 and 44 to each other. However, any component may be used to constrain the members 42 and 44 as long as it is capable of constraining the members 42 and 44. For example, as shown in FIG. 3 , an outer ring 52 may be used instead of the outer nut 50. The inner peripheral surface of the outer ring 52 is not threaded. Also, in FIG. 3 , the outer peripheral surface of the cylindrical portion 40 a of the split nut 40 is not threaded. In FIG. 3 , the outer ring 52 is attached to the split nut 40 so that the inner peripheral surface of the outer ring 52 is in close contact with the outer peripheral surface of the cylindrical portion 40 a, thereby constraining the members 42 and 44. In this specification, the outer nut 50 and the outer ring 52 are examples of outer members.

[0023] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0024] 14: stud bolt, 16: bearing surface, 20: masking seal, 30: masking member, 40: split nut, 40a: cylindrical portion, 42: member, 44: member, 50: outer nut

Claims

[Claim 1] A method for cathodic coating a stud bolt, comprising: placing a masking member on a seat surface of the stud bolt; a step of attaching a split nut to the stud bolt, the split nut having a cylindrical portion with a thread groove formed on the inner peripheral surface of a central hole, the cylindrical portion being separable into a plurality of portions in the circumferential direction, such that the thread groove of the central hole engages with the thread groove of the stud bolt and the split nut comes into contact with the masking member; attaching an outer member having a center hole to the split nut so that an inner peripheral surface of the center hole of the outer member contacts an outer peripheral surface of the cylindrical portion; a step of rotating the split nut in a fastening direction relative to the stud bolt to apply pressure to the masking member with the split nut; cathodic coating of the stud bolt in a state where the masking member is pressed by the split nut; A method having the following.

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